1. Field of the Invention
The present invention relates to data transmission schemes and more specifically to a method and apparatus for secure data transmission.
2. Related Art
Information security of wireless communications has become a very important issue with a growing number of wireless communication applications. Due to the broadcast nature of wireless medium, the wireless security is inherently more vulnerable than the wired security. In wireless networks, the eavesdropper may overhear signals transmitted from a transmitter and interpret the messages more easily than in wired networks.
In most of the existing methods to guarantee the security of transmitting signals, a transmitter generates signals coded by cryptography. Both a transmitter transmitting the signals coded by cryptography and a receiver receiving the signals coded by cryptography should have secret key to guarantee the security of the signals. Wireless communication system should perform key management to decode the signal coded by cryptography. However, performing the key management in a wireless communication system can be difficult and complex process. To overcome the difficult and complex operation of the key management in the wireless communication system, physical layer security techniques have been proposed.
Most of the works in the area of physical layer security have focused only on the scenario of point-to-point communications, i.e., the single user case, which typically involves one transmitter and one receiver in the presence of an eavesdropper. The natural extension is to consider multiple users. In particular, the case of multiple (legitimate) receivers, known as the broadcast channel (BC), is an important scenario.
Most of the works in the area of physical layer security are also based on an assumption which the eavesdropper's channel was assumed to be a degraded version of the legitimate user's channel. Later, This assumption should be extended to the non-degraded case, where the eavesdropper's channel is not necessarily a degraded version of the legitimate user's channel, and also applied to Gaussian channels.